渭河断裂深、中、浅和近地表显示
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摘要
渭河断裂是渭河盆地一条重要的隐伏断裂,对渭河盆地的形成和发展乃至盆地内的地震活动都具有一定的控制作用。文中基于横跨渭河断裂的深地震反射、浅层地震反射、钻孔勘探和槽探等勘探方法取得的探测结果,从深部、中部、浅部以及近地表4个深度,给出了渭河断裂的呈现特点,即最深切割层位、不同深度的产状变化、错距大小、断裂的最新活动时代和活动期次等。
The Weihe Fault is an important blind fault in Weihe Basin and controls the formation,evolution and seismicity of Weihe Basin. The deep seismic reflection survey results show that the fault is not a deep crustal fault; it is located right below the C layer at about 15km depth and cuts through the crystalline basement and the C layer,causing a throw of about 4km between the two sides of crystalline basement. The dip angle at the shallow part of the fault(depth<5km)is big and flattens with depth,and the fault turns to be a listric fault.Shallow seismic survey results show that the dip angle of the Weihe Fault in the middle and deep parts is about 85°; the attitude is different on the two walls of the fault,the footwall is horizontal and the hanging wall is tilting to the south direction; and its dip angle increases quickly.Drilling survey results show that the fault at the shallow part is obviously manifested. The lithology,thickness and attitudes of strata are quite different between the two sides of fault. The attitude on the footwall is horizontal and that on the hanging wall tilts a bit to the fault side. The late Pleistocene displacement is about 4～6m.Trenching results show that the Weihe Fault near ground is still active. Since Holocene epoch it has undergone 3 paleoearthquakes and 1 history earthquake,so it is a Holocene active fault.
The Weihe Fault is an important blind fault in Weihe Basin and controls the formation,evolution and seismicity of Weihe Basin. The deep seismic reflection survey results show that the fault is not a deep crustal fault; it is located right below the C layer at about 15km depth and cuts through the crystalline basement and the C layer,causing a throw of about 4km between the two sides of crystalline basement. The dip angle at the shallow part of the fault(depth<5km)is big and flattens with depth,and the fault turns to be a listric fault.Shallow seismic survey results show that the dip angle of the Weihe Fault in the middle and deep parts is about 85°; the attitude is different on the two walls of the fault,the footwall is horizontal and the hanging wall is tilting to the south direction; and its dip angle increases quickly.Drilling survey results show that the fault at the shallow part is obviously manifested. The lithology,thickness and attitudes of strata are quite different between the two sides of fault. The attitude on the footwall is horizontal and that on the hanging wall tilts a bit to the fault side. The late Pleistocene displacement is about 4～6m.Trenching results show that the Weihe Fault near ground is still active. Since Holocene epoch it has undergone 3 paleoearthquakes and 1 history earthquake,so it is a Holocene active fault.
引文
①国家地质总局第三普查勘探大队,1977,汾渭盆地石油普查阶段地质成果报告。
②西北电力设计院,1979,渭河电厂一期工程供水水源地水文地质勘察报告。
③陕西省地质矿产局第一水文地质工程地质队,1987,渭河电厂扩建工程供水西部水源地水文地质勘察报告。
冯希杰.2000.渭河断裂古水断层剖面[J].地震地质,22(2):209—230.FENG Xi-jie.2000.Gushui Fault profile on the Weihe Fault[J].Seismology and Geology,22(2):209—230(inChinese).
冯希杰,戴王强,董星宏.2003a.从陕西省扶风县古水路堑剖面剖析渭河断裂第四纪活动[J].中国地震,19(2):188—193.FENG Xi-jie,DAI Wang-qiang,DONG Xing-hong.2003a.Quaternary activity of the Weihe Fault obtained from theanalysis of Gushui trough profile in Fufeng County,Shaanxi Province[J].Earthquake Research in China,19(2):188—193(in Chinese).
冯希杰,田勤俭,申旭辉.2003b.渭河断裂西段活动差异性分析[J].地质论评,49(3):233—238.FENG Xi-jie,TIAN Qin-jian,SHEN Xu-hui.2003b.Analysis of activity difference of the west section of the WeiheFault[J].Geological Review,49(3):233—238(in Chinese).
国家地震局“鄂尔多斯周缘活动断裂系”课题组.1988.鄂尔多斯周缘活动断裂系[M].北京:地震出版社.114—136.The Research Group on Active Fault System around Ordos Massif,State Seismological Bureau.1988.Active FaultSystem around Ordos Massif[M].Seismological Press,Beijing.114—136(in Chinese).
彭建兵.1992.渭河断裂带的构造演化与地震活动[J].地震地质,14(2):113—120.PENG Jian-bing.1992.Tectonic evolution and seismicity of Weihe Fault zone[J].Seismology and Geology,14(2):113—120(in Chinese).
陕西省地质矿产局.1989.陕西省区域地质志[Z].北京:地质出版社.Bureau of geology and mineral resources of Shaanxi Province.1989.Regional Geology of Shaanxi Province[Z].Geological Publishing House,Beijing(in Chinese).
师亚芹,李晋,冯希杰,等.2007.渭河断裂带古地震研究[J].地震地质,29(3):607—616.SHI Ya-qin,LI Jin,FENG Xi-jie,et al.2007.The study of paleoearthquake on the Weihe Fault zone[J].Seismologyand Geology,29(3):607—616(in Chinese).
严阵.1965.渭河谷地第四纪旋转大断裂[J].中国第四纪研究,4(2):117—118.YAN Zhen.1965.Quaternary big rotatory fault in Weihe valley[J].Quaternaria Sinica,4(2):117—118(inChinese).
张保增,谢振乾,张保卫.1989.西安地区区域稳定性基本估计[J].陕西地质,7(1):77—83.ZHANG Bao-zeng,XIE Zhen-qian,ZHANG Bao-wei.1989.Abasic evaluation of regional crustal stability of Xi an area[J].Geology of Shaanxi,7(1):77—83(in Chinese).
②西北电力设计院,1979,渭河电厂一期工程供水水源地水文地质勘察报告。
③陕西省地质矿产局第一水文地质工程地质队,1987,渭河电厂扩建工程供水西部水源地水文地质勘察报告。
冯希杰.2000.渭河断裂古水断层剖面[J].地震地质,22(2):209—230.FENG Xi-jie.2000.Gushui Fault profile on the Weihe Fault[J].Seismology and Geology,22(2):209—230(inChinese).
冯希杰,戴王强,董星宏.2003a.从陕西省扶风县古水路堑剖面剖析渭河断裂第四纪活动[J].中国地震,19(2):188—193.FENG Xi-jie,DAI Wang-qiang,DONG Xing-hong.2003a.Quaternary activity of the Weihe Fault obtained from theanalysis of Gushui trough profile in Fufeng County,Shaanxi Province[J].Earthquake Research in China,19(2):188—193(in Chinese).
冯希杰,田勤俭,申旭辉.2003b.渭河断裂西段活动差异性分析[J].地质论评,49(3):233—238.FENG Xi-jie,TIAN Qin-jian,SHEN Xu-hui.2003b.Analysis of activity difference of the west section of the WeiheFault[J].Geological Review,49(3):233—238(in Chinese).
国家地震局“鄂尔多斯周缘活动断裂系”课题组.1988.鄂尔多斯周缘活动断裂系[M].北京:地震出版社.114—136.The Research Group on Active Fault System around Ordos Massif,State Seismological Bureau.1988.Active FaultSystem around Ordos Massif[M].Seismological Press,Beijing.114—136(in Chinese).
彭建兵.1992.渭河断裂带的构造演化与地震活动[J].地震地质,14(2):113—120.PENG Jian-bing.1992.Tectonic evolution and seismicity of Weihe Fault zone[J].Seismology and Geology,14(2):113—120(in Chinese).
陕西省地质矿产局.1989.陕西省区域地质志[Z].北京:地质出版社.Bureau of geology and mineral resources of Shaanxi Province.1989.Regional Geology of Shaanxi Province[Z].Geological Publishing House,Beijing(in Chinese).
师亚芹,李晋,冯希杰,等.2007.渭河断裂带古地震研究[J].地震地质,29(3):607—616.SHI Ya-qin,LI Jin,FENG Xi-jie,et al.2007.The study of paleoearthquake on the Weihe Fault zone[J].Seismologyand Geology,29(3):607—616(in Chinese).
严阵.1965.渭河谷地第四纪旋转大断裂[J].中国第四纪研究,4(2):117—118.YAN Zhen.1965.Quaternary big rotatory fault in Weihe valley[J].Quaternaria Sinica,4(2):117—118(inChinese).
张保增,谢振乾,张保卫.1989.西安地区区域稳定性基本估计[J].陕西地质,7(1):77—83.ZHANG Bao-zeng,XIE Zhen-qian,ZHANG Bao-wei.1989.Abasic evaluation of regional crustal stability of Xi an area[J].Geology of Shaanxi,7(1):77—83(in Chinese).
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